How to Bulk Rename File Extensions in Windows 10 & 11

Need to change .txt to .md? .jpeg to .jpg? Here's how to bulk change file extensions safely.

Warning: Extension Changes

Changing extensions doesn't convert files. A .txt file renamed to .pdf won't become a real PDF.

Safe extension changes: - .jpeg → .jpg (same format) - .htm → .html (same format) - .txt → .md (both text)

Method 1: Command Prompt

Change all files in folder

ren *.txt *.md

Specific pattern

ren image*.jpeg image*.jpg

Method 2: PowerShell

Basic extension change

Get-ChildItem *.txt | Rename-Item -NewName { $_.Name -replace '.txt','.md' }

With confirmation

Get-ChildItem *.txt | Rename-Item -NewName { $_.Name -replace '.txt','.md' } -WhatIf

Remove -WhatIf to execute.

Recursive (subfolders too)

Get-ChildItem -Recurse *.txt | Rename-Item -NewName { $_.Name -replace '.txt','.md' }

Method 3: Bulk Rename Utility

1. Open Bulk Rename Utility
2. Navigate to folder
3. Select files
4. In "Extension" section:
5. - Check "Fixed"
6. - Enter new extension
7. Preview changes
8. Click Rename

Common Extension Changes

Image formats

.jpeg → .jpg
.tiff → .tif
.PNG → .png

Document formats

.htm → .html
.txt → .md

Fixing incorrect extensions Sometimes files have wrong extensions. Fixing requires actual conversion, not just renaming.

Showing File Extensions

Before bulk renaming, make extensions visible:

Windows 11 1. Open File Explorer 2. View → Show → File name extensions

Windows 10 1. Open File Explorer 2. View tab → Check "File name extensions"

Safety Tips

1. Back up first - Copy files before changing
2. Test one file - Verify it still opens
3. Use -WhatIf - Preview PowerShell changes
4. Don't change system files - Stick to your documents

Try File Renamer AI - For complete file renaming beyond extensions.